It is has been previously suggested and confirmed in our preliminary data that hepatitis C virus (HCV) transmission is increased in HIV- infected mothers. We have also documented that this transmission is greatest when the child also receives HIV from the mother and experiences the associated immunosuppression. This indicates a possible role for an immune-mediated protection from chronic infection upon exposure to HCV in children with intact immune systems. We have available a relatively large cohort of individuals already recruited into HIV transmission studies who can also provide critical information regarding HCV transmission and pathogenesis. We plan to continue to recruit HCV-infected pregnant women and their offspring into this study to evaluate immune responses in Rreal-timeS assays. In addition to studying the possible role of immune-mediated responses that prevent chronic infection, the elucidation of these responses will allow us to look for evidence of immunologic selective pressures on HCV by also looking for changes in viral load and distribution (i.e., quasispecies predominance) in those who become infected. The lab will be utilized for PCR, oligonucleotide synthesis, DNA isolation, RNA isolation, and recombinant DNA techniques.